plete electrical needs on a net-annual basis. Using net metering, the array is designed to overproduce in electricity during the summer, allowing credit to build with the serving utility. The credit is then drawn upon during winter months when production is lower due to shorter daylight periods and more cloudy days. The Importance of Inverters At the heart of the solar installation are American-made, SMA Sunny Tripower inverters, turning the up-to- 800 V of raw DC energy generated from the solar panels into familiar, clean, and workable 480-V AC energy. The transformerless grid-tieinverters synchronize their output 40 WELDING JOURNAL / JULY 2016 frequency to the utility grid using a local oscillator and limit the voltage for a high-quality match with grid voltage. The inverters’ on-board computers sense the grid’s waveform and adjust the output voltage to match on the fly. The inverters’ output voltage and current are aligned within 1 deg with the grid. Steffensmeier Welding’s industrial electrical equipment cannot tell the difference if energy is coming from the grid or on-site solar installation. The inverters are also equipped with built-in safety features meant to protect utility line workers who are sent out to fix the power grid in case of an outage. If the inverters’ on-board computer detects that the utility grid has gone down, the inverters automatically disconnect from the grid so that no energy transfers down the lines and the inverters stay disconnected until the power grid returns to normal. With no moving parts and solidstate technology, the solar installation is a minimal maintenance, passive energy-generation system, which is one of the reasons the company was attracted to the technology. Linking the Inverters With Iowa’s seasonal weather, any significant dust buildup on the solar panels is washed away with the next rainstorm. There’s not much to do but watch the sunshine and generate electricity, though it can be important and useful to know exactly how the solar installation is performing — Fig. 5. For this purpose, the solar inverters Fig. 2 — Iowa Governor Terry Branstad (far left) spoke at Steffensmeier Welding last year. Pictured next to him are former Production Engineer Glenn Steffensmeier, Owner Jenny Steffensmeier, and Ideal Energy’s Founder and CEO Troy Van Beek. Fig. 3 — This overhead picture, taken during the installation phase, reflects the key-shaped layout chosen for the solar field. Fig. 4 — An Ideal Energy worker carries a solar panel, one of more than 1400 that make up the field, to be placed in its spot. Fig. 5 — A grid of panels, shown at sunset, capture the day’s last sunshine to generate electricity.
Welding Journal | July 2016
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